I. Field of the Invention
The present invention relates to an adapter for attachment to the hub of a vehicle axle for attaching dual wheels to the axle hub.
II. Description of the Prior Art
Virtually all vehicles, such as automobiles, pickup trucks, and the like, include a front and rear axle with a hub at each end for attachment to a single wheel rim of a wheel. Consequently, the entire weight of the vehicle, plus its load, is supported by four wheels, i.e., two front wheels and two back wheels.
When the vehicle is intended to carry heavy loads, however, it is advantageous to provide dual or tandem wheels on the rear axle of the vehicle. Dual wheels virtually eliminate any chance of rear wheel blowouts which is a major cause of pickup camper accidents and the like. Additionally, dual wheels increase the stability and improve the handling of heavily loaded vehicles and also improve traction in both summer and winter. Moreover, the load carrying capacity of the vehicle is increased by dual wheels while simultaneously prolonging tire life.
For two separate reasons, it is virtually impossible to directly secure dual wheels to the axle hub of most vehicles. First, the outwardly extending studs on the axle hub for attaching the wheel rim to the hub are too short to accommodate two coaxially mounted wheel rims as are necessary with dual wheels. Secondly, even if dual wheels could be directly attached to the axle hub, the inner side of the inner wheel would contact and rub against the wheel well of the vehicle.
In order to overcome these above-mentioned problems, there are previously-known wheel adapters for attaching dual wheels to the axle hub of a vehicle and one such adapter is disclosed in U.S. Pat. No. 2,067,620 which issued on Jan. 12, 1937, to S. H. Johnston et al. These previously-known wheel adapters, however, suffer several disadvantages and, as a result, have not enjoyed widespread acceptance or use.
One disadvantage of these previously-known wheel adapters is that these adapters are constructed of cast iron and consequently are relatively expensive to construct. Moreover, cast iron is brittle and after prolonged use tends to fracture which, needless to say, presents a serious safety hazard.
Another disadvantage of these previously-known wheel adapters is that one wheel rim must be mounted between the wheel hub and the adapter while the other wheel rim is mounted to the outwardly extending axial end of the wheel adapter. Consequently, in order to remove the inner wheel from the vehicle, it is necessary to remove not only the outer wheel, but also the wheel adapter. The necessity of removing the wheel adapter in order to remove the inner wheel is not only time consuming, but also awkward in practice.